Merge pull request #2032 from Ivorforce/native-mutex

Add `Mutex` from upstream Godot, and put the upstream `Mutex` into `CoreBind`

Author: dsnopek

binding_generator.py

@@ -1792,7 +1792,10 @@ def generate_engine_class_header(class_api, used_classes, fully_used_classes, us
         result.append("#include <godot_cpp/core/binder_common.hpp>")
         result.append("")
 
-    result.append("namespace godot {")
+    if class_name == "Mutex":
+        result.append("namespace godot::CoreBind {")
+    else:
+        result.append("namespace godot {")
     result.append("")
 
     for type_name in used_classes:
@@ -2102,7 +2105,10 @@ def generate_engine_class_source(class_api, used_classes, fully_used_classes, us
 
         result.append("")
 
-    result.append("namespace godot {")
+    if class_name == "Mutex":
+        result.append("namespace godot::CoreBind {")
+    else:
+        result.append("namespace godot {")
     result.append("")
 
     if is_singleton:

include/godot_cpp/core/mutex_lock.hpp include/godot_cpp/templates/mutex.hppinclude/godot_cpp/core/mutex_lock.hpp renamed to include/godot_cpp/templates/mutex.hpp

@@ -1,5 +1,5 @@
 /**************************************************************************/
-/*  mutex_lock.hpp                                                        */
+/*  mutex.hpp                                                             */
 /**************************************************************************/
 /*                         This file is part of:                          */
 /*                             GODOT ENGINE                               */
@@ -30,27 +30,108 @@
 
 #pragma once
 
-#include <godot_cpp/classes/mutex.hpp>
+#include <godot_cpp/core/defs.hpp>
+
+#ifdef MINGW_ENABLED
+#define MINGW_STDTHREAD_REDUNDANCY_WARNING
+#include <thirdparty/mingw-std-threads/mingw.mutex.h>
+#define THREADING_NAMESPACE mingw_stdthread
+#else
+#include <mutex>
+#define THREADING_NAMESPACE std
+#endif
 
 namespace godot {
 
-class MutexLock {
-	const Mutex &mutex;
+#ifdef THREADS_ENABLED
+
+template <typename MutexT>
+class MutexLock;
+
+template <typename StdMutexT>
+class MutexImpl {
+	friend class MutexLock<MutexImpl<StdMutexT>>;
+
+	using StdMutexType = StdMutexT;
+
+	mutable StdMutexT mutex;
 
 public:
-	_ALWAYS_INLINE_ explicit MutexLock(const Mutex &p_mutex) :
-			mutex(p_mutex) {
-		const_cast<Mutex *>(&mutex)->lock();
+	_ALWAYS_INLINE_ void lock() const {
+		mutex.lock();
+	}
+
+	_ALWAYS_INLINE_ void unlock() const {
+		mutex.unlock();
 	}
 
-	_ALWAYS_INLINE_ ~MutexLock() {
-		const_cast<Mutex *>(&mutex)->unlock();
+	_ALWAYS_INLINE_ bool try_lock() const {
+		return mutex.try_lock();
 	}
 };
 
+template <typename MutexT>
+class [[nodiscard]] MutexLock {
+	mutable THREADING_NAMESPACE::unique_lock<typename MutexT::StdMutexType> lock;
+
+public:
+	explicit MutexLock(const MutexT &p_mutex) :
+			lock(p_mutex.mutex) {}
+
+	// Clarification: all the funny syntax is needed so this function exists only for binary mutexes.
+	template <typename T = MutexT>
+	_ALWAYS_INLINE_ THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &_get_lock(
+			typename std::enable_if<std::is_same<T, THREADING_NAMESPACE::mutex>::value> * = nullptr) const {
+		return lock;
+	}
+
+	_ALWAYS_INLINE_ void temp_relock() const {
+		lock.lock();
+	}
+
+	_ALWAYS_INLINE_ void temp_unlock() const {
+		lock.unlock();
+	}
+
+	// TODO: Implement a `try_temp_relock` if needed (will also need a dummy method below).
+};
+
+using Mutex = MutexImpl<THREADING_NAMESPACE::recursive_mutex>; // Recursive, for general use
+using BinaryMutex = MutexImpl<THREADING_NAMESPACE::mutex>; // Non-recursive, handle with care
+
 #define _THREAD_SAFE_CLASS_ mutable Mutex _thread_safe_;
 #define _THREAD_SAFE_METHOD_ MutexLock _thread_safe_method_(_thread_safe_);
 #define _THREAD_SAFE_LOCK_ _thread_safe_.lock();
 #define _THREAD_SAFE_UNLOCK_ _thread_safe_.unlock();
 
+#else // No threads.
+
+class MutexImpl {
+	mutable THREADING_NAMESPACE::mutex mutex;
+
+public:
+	void lock() const {}
+	void unlock() const {}
+	bool try_lock() const { return true; }
+};
+
+template <typename MutexT>
+class [[nodiscard]] MutexLock {
+public:
+	MutexLock(const MutexT &p_mutex) {}
+
+	void temp_relock() const {}
+	void temp_unlock() const {}
+};
+
+using Mutex = MutexImpl;
+using BinaryMutex = MutexImpl;
+
+#define _THREAD_SAFE_CLASS_
+#define _THREAD_SAFE_METHOD_
+#define _THREAD_SAFE_LOCK_
+#define _THREAD_SAFE_UNLOCK_
+
+#endif // THREADS_ENABLED
+
 } // namespace godot

test/project/main.gd

@@ -313,6 +313,12 @@ func _ready():
 		var przykład = ClassDB.instantiate("ExamplePrzykład")
 		assert_equal(przykład.get_the_word(), "słowo to przykład")
 
+	# Test call some methods on a thread safe class.
+	var example_thread_safe = ExampleThreadSafeClass.new()
+	assert_equal(example_thread_safe.test(), 123)
+	assert_equal(example_thread_safe.test_const(), 456)
+	assert_equal(example_thread_safe.test_manual(), 789)
+
 	exit_with_status()
 
 func _on_Example_custom_signal(signal_name, value):

test/src/example.cpp

@@ -823,3 +823,25 @@ void ExampleInternal::_bind_methods() {
 int ExampleInternal::get_the_answer() const {
 	return 42;
 }
+
+void ExampleThreadSafeClass::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("test"), &ExampleThreadSafeClass::test);
+	ClassDB::bind_method(D_METHOD("test_const"), &ExampleThreadSafeClass::test_const);
+	ClassDB::bind_method(D_METHOD("test_manual"), &ExampleThreadSafeClass::test_manual);
+}
+
+int ExampleThreadSafeClass::test() {
+	_THREAD_SAFE_METHOD_
+	return 123;
+}
+
+int ExampleThreadSafeClass::test_const() const {
+	_THREAD_SAFE_METHOD_
+	return 456;
+}
+
+int ExampleThreadSafeClass::test_manual() {
+	_THREAD_SAFE_LOCK_
+	_THREAD_SAFE_UNLOCK_
+	return 789;
+}

test/src/example.h

@@ -21,6 +21,7 @@
 #include <godot_cpp/classes/tile_set.hpp>
 #include <godot_cpp/classes/tween.hpp>
 #include <godot_cpp/classes/viewport.hpp>
+#include <godot_cpp/templates/mutex.hpp>
 #include <godot_cpp/variant/variant.hpp>
 #include <godot_cpp/variant/variant_internal.hpp>
 
@@ -314,3 +315,17 @@ class ExampleInternal : public RefCounted {
 public:
 	int get_the_answer() const;
 };
+
+class ExampleThreadSafeClass : public RefCounted {
+	GDCLASS(ExampleThreadSafeClass, RefCounted);
+
+	_THREAD_SAFE_CLASS_
+
+protected:
+	static void _bind_methods();
+
+public:
+	int test();
+	int test_const() const;
+	int test_manual();
+};

test/src/register_types.cpp

@@ -32,6 +32,7 @@ void initialize_example_module(ModuleInitializationLevel p_level) {
 	GDREGISTER_RUNTIME_CLASS(ExampleRuntime);
 	GDREGISTER_CLASS(ExamplePrzykład);
 	GDREGISTER_INTERNAL_CLASS(ExampleInternal);
+	GDREGISTER_CLASS(ExampleThreadSafeClass);
 }
 
 void uninitialize_example_module(ModuleInitializationLevel p_level) {